The overall objective of this proposal is to apply the non-invasive dynamic and quantitative capabilities of scintigraphic analysis to on-going animal experimentation by a core group of NIH-funded investigators and avail these capabilities to other potential investigators in the area. Studies of the core investigators include: 1) dynamic function studies of the reticuloendothelial system with special reference to the septic and post-traumatic states; 2) effect of alteration of reticuloendothelial system phagocytic function on the clearance and organ distribution of fibrin and platelets during sepsis and other thrombotic states; 3) the use of radiolabelled opsonic alpha 2 surface binding glycoprotein (cold-insoluble globulin; fibronectin) as a non-invasive imager of foci of tissue injury; 4) the integration of functional and regional pulmonary studies of ventilation and perfusion matching; 5) the dynamic evaluation of clearance and tissue distribution of altered erythrocytes and erythrocyte debris; and 6) scintigraphic assessment of pulmonary embolism and pulmonary edema. The overall thrust of this multidisciplinary research proposal is directed toward understanding of basic pathophysiological mechanisms operating in injured and septic patients during multiple organ failure. This analytical instrument system provides a means for non-invasive in vivo assessment of physiological processes involving the interaction of multiple tissue and organ systems.